This disclosure relates generally to systems and methods for detecting defects in aircraft wiring, and more particularly, to systems and methods for detecting partial discharges or arcing in wiring or cables.
Wiring is a critical system in aircraft, shipboard, industry and home applications. In particular, aircraft wiring integrity and safety related issues have received a great deal of interest. Aircraft wiring insulation is typically much thinner than that found in building wiring, in order to reduce weight. This thin insulation may deteriorate with age due to changes in chemical composition, vibration during flights, large temperature changes, and exposure to agents such as dust, salt, moisture and cleaning chemicals. In addition, aircraft wiring may also be exposed to mechanical stresses during maintenance. The aforementioned effects can degrade the insulation, causing cracks and chafing. These insulation defects, in turn, can cause arcing between wires or surrounding metals. Humidity together with salt and dust depositions can make the arc creation more probable.
Presently, the detection of aircraft wiring defects is primarily performed by visual inspection by maintenance personnel. This manual inspection is a slow process, and its reliability is not always satisfactory. Furthermore, as it requires twisting the wiring in order to check chafing, this visual inspection has the potential to cause problems. Therefore, a need exists for improved defect detection techniques for aircraft wiring.
As discussed for example in commonly assigned U.S. Pat. No. 6,930,610, G. Gao et al., entitled “Monitoring System and Method for Wiring Systems,” which is hereby incorporated by reference, partial discharge signal detection can be used to characterize the condition of wiring. If a partial discharge occurs, the discharge will generate high frequency electrical signals traveling along the cable. This high frequency electrical signal can be detected with high frequency current transformers (HFCTs). However, commercially available current transformers are typically large and heavy and thus not suited for use in aircraft wiring monitoring as a permanently installed sensor.
Accordingly, it would be desirable to provide a relatively low weight high-bandwidth sensor suitable for use in partial discharge monitoring of aircraft wiring.